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MARCKS regulates lamellipodia formation induced by IGF‐I via association with PIP 2 and β‐actin at membrane microdomains
Author(s) -
Yamaguchi Hiroki,
Shiraishi Mitsuya,
Fukami Kiyoko,
Tanabe Atsuhiro,
IkedaMatsuo Yuri,
Naito Yasuhito,
Sasaki Yasuharu
Publication year - 2009
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.21822
Subject(s) - marcks , lamellipodium , lipid raft , microbiology and biotechnology , myristoylation , dephosphorylation , phosphorylation , chemistry , biology , biochemistry , signal transduction , cytoskeleton , cell , phosphatase
Myristoylated alanine‐rich C kinase substrate (MARCKS) is considered to participate in formation of F‐actin‐based lamellipodia, which represents the first stage of neurite formation. However, the mechanism of how MARCKS is involved in lamellipodia formation is not precisely unknown. Using SH‐SY5Y cells, we demonstrated here that MARCKS was translocated from cytosol to detergent‐resistant membrane microdomains, known as lipid rafts, within 30 min after insulin‐like growth factor‐I (IGF‐I) stimulation, which was accompanied by MARCKS dephosphorylation, β‐actin accumulation in lipid rafts, and lamellipodia formation. The protein kinase C inhibitor, Ro‐31‐8220, and Rho‐kinase inhibitors, HA1077 and Y27632, themselves decreased basal phosphorylation levels of MARCKS and coincidently elicited translocation of MARCKS to lipid rafts. On the other hand, the phosphoinositide 3‐kinase inhibitor, LY294002, abolished IGF‐I‐induced dephosphorylation, translocation of MARCKS to lipid rafts, and lamellipodia formation. Treatment of cells with neomycin, a PIP 2 ‐masking reagent, attenuated the translocation of MARCKS to lipid rafts and the lamellipodia formation induced by IGF‐I, although dephosphorylation of MARCKS was not affected. Immunocytochemical and immunoprecipitation analysis indicated that IGF‐I stimulation induced the translocation of MARCKS to lipid rafts in the edge of lamellipodia and formation of the complex with PIP 2 . Moreover, we demonstrated that knockdown of endogenous MARCKS resulted in significant attenuation of IGF‐I‐induced β‐actin accumulation in the lipid rafts and lamellipodia formation. These results suggest a novel role for MARCKS in lamellipodia formation induced by IGF‐I via the translocation of MARCKS, association with PIP 2 , and accumulation of β‐actin in the membrane microdomains. J. Cell. Physiol. 220: 748–755, 2009. © 2009 Wiley‐Liss, Inc.